I tried one of these a few years back.
It had good points and bad, here is my verdict.
Good:
1. Did stop the wind getting up the back of the helmet.
2. Did stop wind noise.
Bad:
1. When you ever come to take it off your helmet and remove the vecro that holds it position, it leaves a horrible sticky residue.
2. Does not give good airflow around the helmet and thus fogs up quickly.
My opinion (and it is my opinion) is get a bigger windscreen or helmet. Don't waste your money on this item, hope this helps!
